Device for regulating the displacement of the fabric feed member in sewing machines



Nov. 20, 1962 A. MORO.

DEVICE FOR REGULATING THE DISPLACEMENT OF THE FABRIC FEED MEMBER IN SEWING MACHINES Filed April 10. 1959 Allorne y United States Patent G DEVICE FOR REGULATING THE DISPLACEMENT OF THE FABRIC FEED MEMBER IN SEWING MACHINES Antonio Moro, Milan, Italy, assignor to S.p.A. Fratelh Borletti, hiilan, Italy Filed Apr. 10, 1959, Ser. No. 805,611 Claims priority, application Italy Apr. 12, 1958 4 Claims. (Cl. 112-210) In known sewing machines, especially of the domestic type, the mechanism for controlling the amplitude of the displacement of the fabric feed member is actuated by a lever, on whose angular movements, in one direction or the other relative to a zero position, depends the amplitude of displacement of the feed member forwards or backwards and therefore the length of the stitch made in the corresponding direction.

Since in practice, for reverse sewing only a few stitches are required for the tacking of the sewing, with the object of avoiding the necessity for the operator having to give special attention with consequent loss of time, devices have already been proposed in which the lever is actuated solely for change-over from forward to reverse sewing, whilst upon releasing the lever forward sewing is automatically resumed.

The present invention has for object a device of this type which enables such operations to be elfected very rapidly and with complete certainty and which at the same time serves to control the limits of the path of the said lever relative to the absolute value of the amplitude of the required displacement of the feed member.

Such a device, which is particularly applicable to sewing machines in which the mechanism for controlling the amplitude of displacement comprises a forked rod for controlling the feed member, which is pivoted on a fulcrum carried by a small rod the position of which is controlled by a manually operated bell crank, is characterised by an arm pivoted at one end on the casing of the machine parallel to the said lever and formed at its other free end in the form of a V, by an eccentric pin mounted parallel to the pivot of the arm of the said bell crank, which is pivoted between the two branches of the said V-shaped end, cooperating with at least one of them under the action of resilient means acting on the said bell crank, and by means for varying at will the relative distance between the vertices of the said V-shaped end and the axis of the said eccentric pin.

According to a further feature of the invention the means for varying the relative distance between the vertices of the V-shaped end of the said arms and the axis of the eccentric pin are constituted by a cylindrical cam solid with a sleeve rotatably mounted externally of the casing of the machine, relative to a fixed graduation, and an extension of the said arm held in engagement with the said cylindrical cam by resilient means.

These and other features will be more clearly understood from the following description of the preferred practical embodiment of the invention, illustrated by way of example in the accompanying drawings, in which:

FIG. 1 shows the device in elevation,

FIG. 2 shows a plan view thereof,

FIG. 3 shows a detail of FIG. 1, with the parts in different positions, and

FIG. 4 is a modification of part of the device of FIG. 1.

The lever for controlling the amplitude of displacement of the feed member is constituted, in known manner, by a bell crank 1 pivoted on the pin 2, about which it can oscillate; to the end of the arm 3 is connected a pin 4 which is connected to one end of a rod 5 pivoted at the other end at 6 on a forked rod 7 which is caused to oscil- 3,064,604 Patented Nov. 20, 1962 late by the trilobate cam 8 about the pin 4, thereby execut ing an axial movement which is transmitted to the fabric feed member (not shown). Such movement is proportional, as is known, to the deflection of the pin 4 from the line a-a adjoining the axis of rotation of the trilobate cam 8 to the axis of the pin 2 of the lever 1; the more the pin 4 is shifted in the direction of the arrow 10, to the right of line aa, the more the stitch length in forward sewing is lengthened, since the axial displacement of the rod 7 increases; the same occurs for reverse sewing when the pin 4 is moved to the other side of the line aa.

With the device according to the present invention, it is possible to arrest the pin 4 in a position of symmetry relative to the line aa, starting from the zero position and proceeding gradually to a position of maximum deflection corresponding to the maximum stitch length afforded by the machine. For this purpose there is provided an arm 11 movable on the pin 12, about which it can oscillate, the free end 18 of which is V-shaped and embraces the pin 4 with the two arms of the V..

A projection 13 on the arm 11 engages under the action of a spring 14, the helicoidal surface 15 of a cylindrical cam 16 fixed on the spindle of a graduated dial 17. When the projection 13 is in contact with the cam 16 at 15, the V-shaped end of the arm 11 is in the position shown in FIG. 1, in which the pin 4 is engaged in the vertex of the V. In this position the displacement of the feed member is zero. When on the contrary the dial 17 is caused to rotate to bring the projeciton 13 into contact with the point 15, the two arms of the V move away from the pin 4 as shown in FIG. 3, and the lever 1 moves under the action of a spring 9 until the pin 4 is arrested against the arm 19 of the V; in this position the stitches in forward sewing are of maximum length.

In order to change from this position to that for maximum stitch length in reverse sewing, it is only necessary to cause the lever 1 to turn in clock-wise direction by actuating the handle 22, which forms an extension of one of its arms, in the direction of the arrow 21 against the action of the spring 9 until the pin 4 abuts against the other arm 20 of the V-shaped end of the arm 11; the arms 19 and 20 of the V are in fact so disposed that for all positions of the arm 11 including the intermediate ones they can be equally and symmetrically displaced from the pivot 4, and therefore there will be equal stitch lengths for forward and reverse sewing, from zero up to the maximum value alforded by the machine.

The value of the stitch length is determined by the graduation to which the dial 17 is set. The inclination of the cylindrical cam 16 is such that the V-shaped end 18 of the arm 11 moves, through rotation of the dial 17 without any other preliminary operation, the pin 4 and therefore the lever 1 into the required position against the resistance of the spring 9, when the lever 1 is to move in accordance with the arrow 21 to shorten the stitch.

When on the contrary it is desired to lengthen the stitch it is sufficient merely to turn the dial 17 in the opposite direction, because the V-shaped end 18 rises while the spring 9 automatically keeps the pin 4 in contact with the arm 19 of the said end.

For controlling the lever 1 for reverse sewing, instead of the device of FIG. 1, with the handle 22 solid with the said lever, there can be employed the modificationillustrated in FIG. 4, in which there is provided an elbow lever 23 fixed at one end to a spindle 24 of a handle 25 outside the casing of the machine and held in contact at the other end with a pin 26 fixed to the lever 1, by a light spring 27. For operation in reverse it is merely necessary to move the handle 25 (FIG. 4) in a direction perpendicular to the plane of the drawing so as to cause the lever 1 to rise, the lever 1 returning automatically 3 to the position for forward operation, after releasing the handle 25.

It is evident that the direction of displacement of the handle 22, or of the handle, 25, can be the reverse of that described, and that the'constructional details can be a machine 'having a V-shaped portion and a projection,

said V-shaped portion operatively connected to said other pin to limit the oscillatory movement of said other pin, biasing means operatively connected to said lever to urge said other pin against said V-shaped portion of said arm, adjustment means mounted on said machine engaging said projection of said arm for adjusting the relative distance between the vertex'of'said 'V-shaped portion and the axis of said other pin, and further biasing means op.- er'atively connected to' said projection for urging said projectiona-gainst said adjustment means.

2. In a sewing machine according to claim 1 further comprising reversing means connected to said lever to operate against said biasing means to reverse the opera tion of said feed member. 7

3. In a sewing machine according to claim 2 in which said reversing means consists of a further pin mounted on said lever, a rotatable handle provided with a spindle mounted on said machine, an elbow lever having one end mounted on said spindle and the other end operatively engaging said further pin, and urging means operativelyconnected to said elbow lever to urge said elbow lever into engagement with said further pin.

4. In asewing machine according to claim 1 in which said adjustment means consists of a cylindrical cam having a helicoidal surface on which said projection rides, a spindle connected to said cam, and a graduated dial mounted on said spindle on the exterior of said machine to rotate said cam.

References Cited in the file of this patent UNITED STATE-S PATENTS Ivandick May 13, 1947 

